The present invention relates to a control apparatus for a vehicle electric power generator that can control the amount of electric power supplied to a vehicle-driving assist motor.
There is a known method of reducing the output of an engine by using an electronically controlled throttle or the like, in which, when the load on the engine decreases, an increase in engine speed and a slipping of the wheels will be avoided or minimized.
A control method for preventing engine stall, which tends to occur when the electric power output of the electric power generator used in a vehicle is abruptly increased in an attempt to augment the driving force of its motor abruptly, is also disclosed in Japanese Application Patent Laid-open Publication No. 2000-142155.
In a vehicle having an electric power generator connected to the engine for driving the vehicle, reduction in the amount of electric power to be generated is likely to reduce the electric power generating torque of the generator, thereby causing the torque of the engine to become correspondingly excessive, and resulting in the engine speed being increased, the vehicle being abruptly accelerated, and a feeling of uneasiness being given to the driver.
These events are particularly prone to occur in a vehicle that is so constructed that either the front or rear wheels are driven by the engine and the other wheels not driven by the engine are driven by a motor to which electric power is supplied from an electric power generator driven by the engine. For vehicles of this type, since the electric power generating torque of the power generator is large, excessive engine torque generated when the torque generated by the motor decreases will also become significant.
Accordingly, when the torque of the motor is abruptly reduced, the torque of the wheels driven by the engine will also increase significantly, and such abrupt increases in engine speed and abrupt acceleration of the vehicle, that the driver does not intend, may occur. In extreme cases, as shown in FIG. 9, the wheels driven by the engine slip, and the acceleration of the vehicle becomes unstable.
The present inventors have newly discovered the above-described problems in the control of a vehicle that is constructed so that either one of the rear wheels is driven by the engine and the other wheels not driven by the engine are driven by a motor to which electric power is supplied from an electric power generator driven by the engine.
With regard to the foregoing problems, however, although it is easily conceivable to reduce the torque of the engine by using an electronically controlled throttle, this method has the disadvantage that the acceleration characteristics easily deteriorate. Also, an electronically controlled throttle is required for the control of the engine, and the control itself becomes complex.